General: Air diffusers shall be of the sizes shown on the drawings. Units shall have factory catalog performance ratings, which conform to CFM, temperature and velocity profiles, static pressure drop, and generated noise criteria designated. The diffusers shall be a high induction type, specifically designed for air distribution at temperatures down to 35 degrees Fahrenheit, without dumping or forming condensation on the diffuser’s surfaces and provide Air Distribution Performance Index (ADPI*) above 95 at primary supply air volumes down to .10 CFM/ft.

Construction: The Diffusers shall be constructed of a fire retardant material and shall be able to pass the UL 25/50 Flame and Smoke Spread Tests. Plenums shall be factory constructed with inlet collars sized as scheduled. Internal surfaces shall be thermally and acoustically insulated with glass fiber material. The plenum shall be completely sealed to provide a vapor barrier and avoid air leakage. Plenums shall be insulated to provide an overall R 4.5 value at 40 degrees Fahrenheit.

Ceiling Compatibility: Provide diffusers with border styles that are specifically manufactured to fit into ceiling module with accurate fit and adequate support. Refer to general construction drawings and specifications for types of ceiling systems which will contain each type of ceiling air diffuser.

Performance Rating: Performance of the Air diffusers shall be based on independent laboratory tests of factory built plenum/diffuser assemblies run in accordance with ADC** Standard 1062R4.

The diffusers shall be capable of supplying 35 degree Fahrenheit air directly into a room without any tendency for the supply air envelope to drop, "dump", or fall into the room. This shall be accomplished throughout its entire operating range from complete shutoff to one hundred percent flow.

The diffusers shall be capable of providing and ADPI of 95 or above in any room, when selected and located in accordance with the standard Thermal Core procedure. The diffusers shall be capable of providing secondary room air motion and temperature profile from the floor to the seven foot high level evenly maintained at any point in the conditioned area, and confirmed in an ADC certified, independent laboratory test room. See Test Data.

The diffusers shall be capable of supplying 35-degree Fahrenheit air directly into a room without condensation forming on its surfaces.

Types: Provide ceiling diffusers of type, capacity, performance, and with accessories and finishes as listed on Air Distribution Schedule.

Requests for substitution of the specified diffusers shall be accompanied by independent ADC certified laboratory test data, documenting the performance in this specification will be complied with. Calculations, either computerized or manual, shall be submitted fore each conditioned room assuring that the minimum ADPI listed in the schedule will be achieved by the substitute.diffusers.

*Air Diffusion Council
**"ADPI" as described in the 1989 ASHRAE Fundamentals Handbook, Chapter 31